Offences involving sex producing protests (3-3)
I believe the answer is:
sit-ins
'protests' is the definition.
(sit-in is a kind of protest)
'offences involving sex' is the wordplay.
'offences' becomes 'sins' (moral offences).
'involving' means one lot of letters goes inside another.
'sex' becomes 'it' (a common euphemism).
'sins' enclosing 'it' is 'SIT-INS'.
'producing' is the link.
(Other definitions for sit-ins that I've seen before include "In these protests, demonstrators refuse to leave a building" , "Obstructive protests" , "Forms of civil disobedience in which demonstrators refuse to leave a building" .)